It is usually desirable to arrange the drive assembly of ship engines towards the stern of the vessel. Also, the overall height of the power train should be maintained within as low limits as possible. A typical drive arrangement normally comprises a motor having either a deep or a shallow oil pan or sump. In accordance with the available space, the design of the stern part of the vessel is governed by the type of oil pan that is used, either deep or shallow and either a transmission arrangement having parallel input and output shafts or a transmission arrangement having inclined input and output shafts with respect to each other will provide the desired space-saving solution. To date, the prior art has failed to provide a transmission system which can readily achieve the two transmission systems without resorting to duplication in design and construction.
In known reversing gear transmissions, as briefly defined above, the output shaft is inclined with respect to the input shaft and the intermediate shaft, as shown in German published patent application (DT-OS) No. 2,059,820 and German published patent application (DT-OS No. 2,358,778. A bevel gear mounted on the inclined output shaft meshes with a spur gear mounted on the input shaft and the spur gear of the intermediate shaft, which latter spur gear is preferably also formed as a bevel gear. The intermediate shaft is linked, in turn, by a further pair of gears with the input shaft. As the direction of motion of the system is selected, the output shaft is actuated either by the gear on the input shaft or by the gear on the output shaft.
A further transmission assembly is shown in German published patent application (DT-OS) No. 1,909,414 in which it is disclosed to exchange the output shaft and the input shaft together with their respective components in order to achieve a stream-lined design. Both shafts are, however, parallel with respect to each other and, thus, the relative position of the input shaft and the output shaft remains the same, i.e. parallel.
Another transmission arrangement for ships is described in MTZ, Vol. 35, No. 11, 1974 on page 382. In this arrangement, the output shaft is inclined with respect to one of the several other shafts and the output shaft is parallel with respect to a third shaft whereby one of the two shafts is functioning as input shaft and the other as intermediate shaft. This known transmission does not provide for reversing in the system and it does not afford utilization of the transmission, selectively, as transmission having parallel or inclined main shafts, through the exchange of the input shaft components with intermediate shaft components.